1. Field of the Invention
This invention relates to variable attenuators in the electronics and communication fields, and more particularly, to microstrip variable attenuators suitable for use in various high frequency and/or microwave circuits and systems.
2. Description of the Related Art
In the family of electronic components, the variable attenuator is one of the common and basic components in electrical circuits and systems. The existence of a variable attenuator makes the fabrication of electrical circuits and the debugging of systems more flexible and convenient. Currently, the variable attenuator is being widely used in circuits and systems with operating frequencies below a few hundred megahertz (MHz). For example, in CATV (Community Antenna Television) systems and microwave circuits, the variable attenuator is used for testing, regulating power levels, increasing isolation, etc. However, as the operating frequency is in a comparatively high frequency band, the current three-dimensional variable attenuator which is made of a contact spring, a slide block, a guide screw, and so on, has the drawbacks of large parasitic parameters and comparatively poor high frequency characteristics.